The need in drawing, painting and writing exists as long as the human being himself and will exist as long as human being will exist. The graphical or painted in color image cannot be explained or interpreted by the other means, for example by voice, for inputting in the computer. That is why people are searching and will be always searching for newer technologies satisfying this need.
However, until now all painting art is 2D due to the 2D nature of all known canvases (more precisely surface related even it is not a plane but, for example, cylindrical or spherical surfaces). One of the challenges of painting always was how to create an image of the third dimension, the illusion of the depth of the picture. Although a number of great painters achieved fantastic results on this path, nevertheless the interest to 3D visual images, probably existed always, resulted in sculpture and architecture first. However painted sculptures didn't receive wide spread. Then realization of 3D or stereo vision with the advent of photography, when two photo-cameras, placed on a distance of about distance between the human eyes, made two pictures and then these pictures were viewed through the stereoscope invented in 1838.
The huge progress in stereo photography and stereo movie was achieved for the last 170 years. Latest achievements in 3D movies and 3D TV are making an interest to these technologies even greater because it becomes available on an individual level.
However, there were not many achievements on the front of 3D painting mostly because nothing changed in dimensionality of 2D canvas for painting.
There are several challenges for solving the problem of 3D free-hand painting and drawing. The first challenge is a 3D canvas for a free-hand painting and drawing on or within this canvas.
It is hard to imagine, from the existing technology viewpoint, the kind of media, which is true 3D (cube), transparent and allowing penetrating inside this cube with brush, making a stroke of paint and removing the brush without disturbing the rest of the media. It sounds like a science fiction, at least from the modern technology and known materials viewpoint. Otherwise it would bring us back to painted sculptures, which required to make the sculpture, first and then paint it.
As known, depth perception, as visual ability to perceive the world in three dimensions (3D), arises from a variety of depth cues. From all the depth cues both monocular and binocular stereopsis found the most practical applications. Stereopsis is the process in visual perception leading to the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. The differences in the two retinal images are called horizontal disparity, retinal disparity, or binocular disparity. The differences arise from the eyes' different positions in the head.
These two images corresponding to different visions of the right and left eyes are relatively easy to create by stereo-photography or stereo-movie by taking two pictures simultaneously with two cameras separated horizontally similar to two separated eyes. However, it is hard to imagine how an artist can paint two paintings of the same image on two different canvases for two eyes such that they later could be viewed with one of the stereoscopic viewing system.
As long as art of painting exists almost all artists were trying to introduce their techniques of 3D illusion on the 2D flat picture proving the existence of a need for a 3D painting technique. Therefore, there is a need for creating a method and system for 3D painting.